HomeMy WebLinkAboutBLD2015-00042 - 05 STORMWATER • •
co,, DEPARTMENT OF COMMUNITY DEVELOPMENT
621 Sher don Stmct.Pott'fownsend,Ar'.A 98368
Tel:360.3'9.4430 t Fax: 360.3'9.4451 -
Web:www.co.iefferson.wa.us/communitydevclopment
I'.-mail:dcd2.co.icffcrson.wa.us
STORMWATER CALCULATION WORKSHEET
MLA# PROJECT/APPLICANT NAME:
DETERMINING STORM WATER MANAGEMENT REQUIREMENTS:This stormwater calculation worksheet should be completed first to
classify the proposal as "small," "medium," or "large." The size determines whether a Stormwater Site Plan is required in
conjunction with a stand-alone stormwater management permit application, building permit application,or other land use approval
application that involves stormwater review. The basic information will also be helpful for completing a Stormwater Site Plan, if
required.
PARCEL SIZE (I.E., SITE)
Size of parcel 5.5 acres An acre contains 43,560 square feet. Multiply the acreage by this figure.
Size of parcel in square feet 239,580 sq/ft
Land-disturbing activity is any activity that results in movement of earth,or a change in the existing soil cover (both vegetative and
non-vegetative)and/or the existing soil topography. Land disturbing activities include, but are not limited to clearing,grading,filling,
excavation,and compaction associated with stabilization of structures and road construction.
Native vegetation is vegetation comprised on plant species,other than noxious weeds, that are indigenous to the coastal region of
the Pacific Northwest and which reasonably could have been expected to naturally occur on the site. Examples include species such
as Douglas fir, western hemlock, western red cedar, alder, big-leaf maple, and vine maple; shrubs such as willow, elderberry,
salmonberry,and salal; herbaceous plants such as sword fern,foam flower,and fireweed.
LAND DISTURBING ACTIVITY,CONVERSION OF NATIVE VEGETATION,AND VOLUME OF CUT/FILL
Calculate the total area to be cleared, graded,filled, Answer the following two questions related to
excavated,and/or compacted for proposed development conversion of native vegetation:
project. Include in this calculation the area to be cleared for:
1 568 Does the project convert acres or more of
Construction site for structures ' sq/ft native vegetation to lawn or landscaped areas?
Drainfeld,septic tank,etc. 0 sq/ft Circle: Yes No
Well, utilities,etc. 0 sq/ft Does the project convert 2'/acres or more of
1,030 native vegetation to pasture?
Driveway, parking, roads, etc, r sq/ft
Circle: Yes No
Lawn, landscaping, etc. 0 sq/ft
Other compacted surface,etc. 0 sq/ft Indicate Total Volumes of Proposed:
Total Land Disturbance 2,598 sq/ft Cut Fill (cu/yd)
Impervious surface is a hard surface that either prevents or retards the entry of water into the soil mantle as under natural
conditions prior to development. A hard surface area which causes water to run off the surface in greater quantities or at an
increased rate of flow from the flow present under natural conditions prior to development. Common impervious surfaces include,
but are not limited to roof tops, walkways, patios, driveways, parking lots or storage areas,concrete or asphalt paving,gravel roads,
packed earthen materials,and oiled,macadam or other surfaces which similarly impede the natural infiltration of stormwater.
stormwater talc worksheet—REV.10/20/2014 1
• •
STORMWATER CALULATIONS– IMPERVIOUS SURFACE
NEW EXISTING
Structures(all roof area) 496 sq/ft Structures(all roof area) 2,990 sq/ft
Sidewalks 0 sq/ft Sidewalks 0 sq/ft
Patios 0 sq/ft Patios 0 sq/ft
Solid Decks 0 sq/ft Solid Decks 0 sq/ft
(without infiltration below) (without infiltration below)
Driveway, parking, roads,etc 970 sq/ft Driveway, parking, roads, etc 5,920 sq/ft
Other 0 sq/ft Other 1,440 sq/ft
Total New
1,466 sq/ft Total Existing 10,350 sq/ft
TOTAL NEW+ TOTAL EXISTING" 11 ,816 sq/ft *This amount will be used to check total lot coverage.
/
The following questions will help determine whether the proposed project is considered development or redevelopment.
DEVELOPMENT v. REDEVELOPMENT
Divide the total existing impervious surface above by the size of the parcel and convert to a percentage: '3 %
Does the site have 35%or more of existing impervious surface? Circle: Yes ❑ No I I
FURTHER INSTRUCTIONS: If the answer is yes,the proposal is considered redevelopment and the attached Figure 2 should be used
to determine the applicable Minimum Requirements. If the answer is no, the proposal is considered new development and the
attached Figure 1 should be used. At this juncture, the applicant should refer to the applicable Flow Chart to determine the
Minimum Requirements for stormwater management. DCD staff will help verify the classification of the project and the application
requirements.
For proponents of "small" projects who must comply only with Minimum Requirement #2—Construction Stormwater Pollution
Prevention—an additional submittal is not required. The proponent is responsible for employing the 12 Elements to control erosion
and prevent sediment and other pollutants from leaving the site during the construction phase of the project. Pick up the
Construction Stormwater Pollution Prevention (SWPP) Best Management Practices (BMPs) Packet. Proponents of "medium"
projects—those that must meet only Minimum Requirements#1 through#5—and for"large" projects—those that must meet all 10
Minimum Requirements—are required to submit a Stormwater Site Plan. DCD has prepared a submittal template of a Stormwater
Site Plan, principally for rural residential projects. Complete the template in the Stormwater Site Plan Instructions and Submittal
Template or prepare a Stormwater Site Plan using the step-by-step guidance in the Stormwater Management Manual.
APPLICANT SIGNATURE
By signing the Stormwater Calculation Worksheet,I as the applicant/owner attest that the information provided herein is true and correct to the
best of my knowledge. I also certify that this application is being made with the full knowledge and consent of all owners of the affected
property. ,�I-
�t v�rlc R l ilk, t�- 'L 1//%lir
( WNER OR AUT RIZED REPRESENTATIVE SIGNATURE) (DATE)
FOR OFFICE USE ONLY
SMALL MEDIUM LARGE REDEVELOPMENT Stormwater Site Plan: Yes No
stormwater calc worksheet—REV.10f20/2014
• •
FIGURE 1 : NEW DEVELOPMENT
Start Here
1r
Does the site have Yes See Redevelopment
35%or more of - 0 Minimum
existing impervious Requirements and
coverage? Flow Chart
(Figure 2)
No Does the project convert 3/a
acres or more of native
vegetation to lawn or
Does the project add No landscaped areas, or
5,000 square feet or convert 2.5 acres or more
•
more of new of native vegetation to
impervious surfaces? pasture?
Yes Yes No
Does the project have
•
2,000 square feet or
"LARGE" PROJECT more of new, replaced,
All Minimum Requirements or new plus replaced
apply to the new impervious impervious surfaces?
surfaces and converted
pervious surfaces. Yes No
•
"MEDIUM" PROJECT Does the project have
Minimum Requirements #1 land-disturbing
through#5 apply to the new activities of 7,000
and replaced impervious Yes square feet or more?
surfaces and the land
disturbed. No
•
"SMALL" PROJECT
See Minimum
Requirement#2,
Construction Stormwater
Pollution Prevention
Based on Fig.2.2 from 2001 Ecology Stormwater Management Manual for Western Washington
• •
(w °N %,� JEFFERSON COUNTY
4 -r DEPARTMENT OF COMMUNITY DEVELOPMENT
621 Sheridan Street-Port Townsend•Washington 98368
360!379.4450•360/379-4451 Fax
�L93�NG�� http://www.co.jeffersonwa.us/commdevetopment/
STORMWATER SITE PLAN SUBMITTAL TEMPLATE
MLA# PROJECT/APPLICANT NAME:
Project Overview
1. Describe the proposed developed conditions of the site. Indicate position and
relative size of proposed improvements on the site map.
The project site is located at 1452 Gardiner Beach Road; parcel number 002-284-020.
The lot is 5.5 acres in size with 10,350 sq. ft. (approximately 4.3%) of existing
impervious surfaces. There is an existing single family residence (SFR), gravel
driveway, and concrete slab. The proposed garage will be built in the location of the
existing slab (area= 1,440 sq. ft.). The garage is 1,568 sq. ft. with 1,936 sq. ft. of roof
area. There is an existing cleared area that is approximately 1.29 acres in size (56,192
sq.ft.). Approximately 1,466 sq. ft. of new impervious surfacing will be added, 970 sq. ft.
of driveway and an additional 496 impervious area(1,936 sq. ft. roof— 1,440 existing
slab), resulting in a 0.6% increase in impervious area (total 4.9%).
Existing Conditions Summary
2. Describe the existing topography. Indicate contours on the site map.
The site generally slopes north with an average slope of 10%.
3. Describe the existing vegetation. Indicate native vegetation areas on the site map.
Surrounding the proposed construction site and SFR are second growth trees and dense
vegetation. The previously cleared area has established grasses and shrubs.
4. Describe the existing soils. Indicate soil type on the site map.
Soils on site are classified by Jefferson County as Tukey gravelly loam (TuC). A typical
profile is described below:
• 0—2 inches: gravelly loam
• 2 — 8 inches: gravelly loam
i •
• 8—36 inches: very gravelly loam
• 36 — 60 inches: very gravelly loam
5. Describe the existing site hydrology (i.e., drainage; behavior of water on the
site—above, below, and on the ground). Indicate existing stormwater drainage to
and from the site on the site map. Depict separate drainage basins on the site map,
if applicable, and indicate acreage of each.
Stormwater onsite generally drains from south to north. There is a 400 foot (3.4 acres)
flow path to the north consisting of second growth trees and dense vegetation; little to no
stormwater leaves the site.
6. Describe any excess levels of noise generated by the proposed use or activity:
Excess noise will strictly be from construction. After completion of construction and
stabilization of disturbed soils, there will be no excess levels of noise.
7. Describe significant geographic features and critical areas (i.e., environmentally
sensitive areas such as wetlands, streams, steep slopes, etc.) on the site. Indicate
location on the site map.
None
8. Describe the general vicinity of the site, including adjacent land uses and
structures, utilities, roads, and sensitive/critical areas (streams,wetlands, lakes,
steep slopes, etc.).
There are no known critical or sensitive areas within or surrounding the property.
Adjacent properties are developed for rural (SFRs) use.
• •
Permanent Stormwater Control Plan
This portion of the Stormwater Site Plan consists of the selection and installation of
the appropriate stormwater control BMPs and facilities to remain in place after
construction of the project is completed.
"Medium" size projects are required to have the totals calculated of all impervious
surfaces, pollution-generating impervious surfaces, and pollution-generating
pervious surfaces to verify that the thresholds for treatment facilities and flow
control facilities are not exceeded.
9. Describe the developed site hydrology, as proposed. Indicate whether
stormwater will be fully dispersed (i.e., per BMP T5.30 in the Manual) or, if not,
what types of stormwater flow control will be utilized for the site or specific
threshold discharge areas within the site. Locate these facilities on the site plan and
differentiate proposed facilities from existing facilities.
Developed site hydrology will mimic pre-construction conditions. Drainage will flow
south to north. Runoff from the garage roof will be collected in downspouts and
discharged onto splash blocks in compliance with BMP T5.10B, and Section 3.1.2 of
Volume III of the Stormwater Management Manual for Western Washington(DOE,
August 2012). Runoff from the gravel access will sheet flow west toward a 2' transition
zone that will disperse the sotrmwater west/northwest in compliance with BMP T5.12.
10. If the project requires the use of stormwater treatment facilities, describe the
types of stormwater treatment facilities proposed for use on the site. Locate these
facilities on the site plan and differentiate proposed facilities from existing facilities.
[This is normally for"large" projects or projects that involve the potential for
dispersion of contaminants.]
N/A, less than 5,000 sq. ft. pollution generating hard surfaces.
•
11. Describe the performance goals and standards applicable to the project.
N/A
12. Describe the flow control system.
N/A
13. Describe the water quality system.
N/A
14. Describe the conveyance system analysis and design.
• •
N/A, full dispersion will be utilized
15. Describe the source of fill material, physical characteristics of fill material, and
deposition of excess material.
N/A
16. Proposed methods of placement and compaction consistent with the applicable
standards on Appendix Chapter 33 of the Uniform Building Code.
N/A
17. Describe the proposed surfacing material.
Surfacing for access to the proposed garage will be clean gravel.
18. Describe methods for restoration of the site.
In compliance with BMP T5.13 a minimum of 8 inches of top soil will be use to amend
disturbed soils. The top soil will be mulched and seeded for final stabilization.
19. An Operation and Maintenance Manual is required for each flow control and
treatment facility. [This is normally required for"large" projects only and only
those for which facilities are required to control flow or treat runoff.] If included,
list the Manuals here.
N/A
20. List here and include any special reports or studies conducted to prepare the
Stormwater Site Plan.
None
21. List other necessary permits and approvals as required by other regulatory
agencies. If those permits or approvals include conditions that affect the drainage
plan or contain more restrictive drainage-related requirements, describe those
conditions or restrictions here.
None
•
CONSTRUCTION STORMWATER POLLUTION PREVENTION
PLAN (SWPPP)
The Construction SWPPP addresses sediment and erosion control during construction.
The BMPs indicated by the applicant in the template that follows must be installed on the
ground during all construction phases of the project. The proponent is responsible for
preventing sediment and erosion impacts to environmentally sensitive areas and off-site
areas. Consult the Construction Stormwater Pollution Prevention(SWPP) Best
Management Practices(BMPs) Packet for guidance, particularly with rural residential
development.
SECTION I - CONSTRUCTION SWPPP NARRATIVE
1. Construction Stormwater Pollution Plan Elements. Describe how each of the
Construction SWPPP elements has been or will be addressed. Identify the type and
location of BMPs used to satisfy the required element. If an element is not applicable
to the proposal,justify in writing. Descriptions of the 12 Elements are found at section
2.5.2 of the Manual (beginning on page 2-15).
12 Required Elements — Construction SWPPP
1. Mark Clearing Limits.
No clearing activity will be needed for the proposal. Construction limits will be kept
close to the construction site in an effort to minimize site disturbance. If needed a 20'
offset will be staked and flagged to delineate the project area and approximate limits of
soils stabilization.
2. Establish Construction Access.
An existing gravel entry will be utilized as an established construction access and staging
area. The existing gravel driveway will be resurfaced as needed to prevent trackout..
3. Control Flow Rates.
Flow control is not needed for this proposal. All runoff will be fully dispersed.
4. Install Sediment Controls.
The dense woods and vegetation to the north will act as a natural vegetative strip in lieu
of a silt fence.
5. Stabilize Soils.
Disturbed soils will be amended in compliance with BMP T5.30 and mulched and seeded
for final stabilization.
• •
6. Protect Slopes.
N/A
7. Protect Drain Inlets.
N/A
8. Stabilize Channels and Outlets.
N/A
9. Control Pollutants.
N/A
10. Control De-Watering(the act of pumping groundwater or stormwater away
from an active construction site).
N/A
11. Maintain Best Management Practices (BMPs).
All BMP's will be checked bi weekly and after major storm events. Any damages or
deficiencies will be addressed promptly.
12. Manage the Project.
All BMP's will be inspected and maintained, temporary BMP's will be removed upon
confirmation of soil stabilization.
Adjacent Areas.
a. Description of the adjacent areas that may be affected by site disturbance
(e.g., streams, lakes, wetlands, residential areas, roads).
None known
• •
b. Description of the downstream drainage path leading from the site to the
receiving body of water (minimum distance of 400yards).
Water sheet flows north into dense woods.
Environmentally Sensitive Areas.
a. Description of environmentally sensitive areas that are on or adjacent to the site.
None known
b. Description of special requirements for working in or near environmentally
sensitive areas.
None
Erosion Problem Areas. Description of potential erosion problems on site in the
context of the characteristics of the on-site soils (e.g., erodibility, settleability,
permeability, depth, texture, soil structure).
None
Construction Phasing.
a. Construction sequence: Resurface gravel driveway as needed to prevent track out,
demolish and remove existing concrete foundation (if applicable), construct proposed
garage, amend disturbed soils, seed and mulch amended soil.
b. Construction phasing(if proposed)
Construction Schedule. Wet season is October 1 through April 30 (page 2-21 of
the Manual).
I. Provide a proposed construction schedule.
January 2015 —July 2015
II. Wet Season Construction Activities.
a. Proposed wet season construction activities:
None
b. Proposed wet season construction activities for environmentally sensitive areas.
N/A
•
Financial/Ownership Responsibilities.
a. Identify the property owner responsible for the initiation of bonds and/or other
financial securities.
The property owner will be responsible for the initiation of bonds and/or other financial
securities.
b. Describe bonds and/or other evidence of financial responsibility for liability
associated with erosion and sedimentation impacts.
The contractor retained by the property owner will be held responsible for bonds and/or
evidence of financial responsibility for liability associated with erosions and
sedimentation impacts.
8. Engineering Calculations. Provide Design Calculations on a separate sheet for
the following, if applicable.
a. Sediment Ponds/Traps.
b. Diversions.
c. Waterways.
d. Runoff/Stormwater Detention Calculations
• !
Map Unit Description:Tukey gravelly loam,0 to 15 percent slopes---Jefferson County Area,
Washington
Jefferson County Area, Washington
TuC—Tukey gravelly loam, 0 to 15 percent slopes
Map Unit Setting
National map unit symbol: 2gtm
Mean annual precipitation: 21 inches
Mean annual air temperature: 50 degrees F
Frost-free period: 225 to 250 days
Farmland classification: Farmland of statewide importance
Map Unit Composition
Tukey and similar soils: 100 percent
Estimates are based on observations, descriptions,and transects of the
mapunit.
Description of Tukey
Setting
Landform: Terraces
Parent material: Basal till
Typical profile
H1 -0 to 2 inches: gravelly loam
H2-2 to 8 inches: gravelly loam
H3-8 to 36 inches: very gravelly loam
H4-36 to 60 inches: very gravelly loam
Properties and qualities
Slope: 0 to 15 percent
Depth to restrictive feature: 20 to 40 inches to densic material
Natural drainage class: Moderately well drained
Capacity of the most limiting layer to transmit water(Ksat): Very low
to moderately low(0.00 to 0.06 in/hr)
Depth to water table: About 18 to 36 inches
Frequency of flooding: None
Frequency of ponding: None
Available water storage in profile: Low(about 3.9 inches)
Interpretive groups
Land capability classification (irrigated): None specified
Land capability classification (nonirrigated): 3e
Hydrologic Soil Group: C
Other vegetative classification: Droughty Soils (G002XN402WA)
Data Source Information
Soil Survey Area: Jefferson County Area, Washington
Survey Area Data: Version 13, Sep 30, 2014
tSDA Natural Resources Web Soil Survey 1/16/2015
Conservation Service National Cooperative Soil Survey Page 1 of 1
• •
�¢g0N 00 DEPARTMENT OF COMMUNITY DEVEL 'Yi>GNT
W<4. a 621 Sheridan Street,Port Townsend,WA 98368 j FEB 3 2015 IL Tel:360.379.4450 I Fax:360.379.4451 L4
Web:www.co.Jefferson.wa.us/communitydevclopmcnt �_.,__
I:-mail:dcd@co.iefferson.wa.us )E E, 0;GUIVTY
® IrPT.O�CCMMUNIIYF.VELOPMENT
,1 N���
STORMWATER CALCULATION WORKSHEET
MLA It PROJECT/APPLICANT NAME:
DETERMINING STORMWATER MANAGEMENT REQUIREMENTS:This stormwater calculation worksheet should be completed first to
classify the proposal as "small," "medium," or "large." The size determines whether a Stormwater Site Plan is required in
conjunction with a stand-alone stormwater management permit application, building permit application,or other land use approval
application that involves stormwater review. The basic information will also be helpful for completing a Stormwater Site Plan, if
required.
PARCEL SIZE(I.E..SITE1
Size of parcel 5.5 acres An acre contains 43,560 square feet. Multiply the acreage by this figure.
Size of parcel in square feet 239'580 sq/ft
Land-disturbing activity is any activity that results in movement of earth, or a change in the existing soil cover(both vegetative and
non-vegetative)and/or the existing soil topography. Land disturbing activities include,but are not limited to clearing,grading,filling,
excavation,and compaction associated with stabilization of structures and road construction.
Native vegetation is vegetation comprised on plant species,other than noxious weeds,that are indigenous to the coastal region of
the Pacific Northwest and which reasonably could have been expected to naturally occur on the site. Examples include species such
as Douglas fir, western hemlock, western red cedar, alder, big-leaf maple, and vine maple; shrubs such as willow, elderberry,
salmonberry,and salal; herbaceous plants such as sword fern,foam flower,and fireweed.
LAND DISTURBING ACTIVITY.CONVERSION OF NATIVE VEGETATION.AND VOLUME OF CUT/FILL
Calculate the total area to be cleared, graded,filled, Answer the following two questions related to
excavated,and/or compacted for proposed development conversion of native vegetation:
project. Include in this calculation the area to be cleared for:
1 568 Does the project convert 3/1 acres or more of
Construction site for structures ' sq/ft native vegetation to lawn or landscaped areas?
Drainfield,septic tank,etc. 0 sq/ft Circle: Yes No
Well, utilities,etc. 0 sq/ft Does the project convert 2 Y acres or more of
1,030 native vegetation to pasture?
Driveway, parking, roads, etc. sq/ft
Circle: Yes
gP
Lawn, landscaping,etc. 0 sq/ft
Other compacted surface, etc. 0 sq/ft Indicate Total Volumes of Proposed:
Total Land Disturbance 2,598 sq/ft Cut 0 Fill 0 (cu/yd)
Impervious surface is a hard surface that either prevents or retards the entry of water into the soil mantle as under natural
conditions prior to development. A hard surface area which causes water to run off the surface in greater quantities or at an
increased rate of flow from the flow present under natural conditions prior to development. Common impervious surfaces include,
but are not limited to roof tops,walkways, patios,driveways,parking lots or storage areas,concrete or asphalt paving,gravel roads,
packed earthen materials,and oiled,macadam or other surfaces which similarly impede the natural infiltration of stormwater.
stor,rweter talc worksheet—REV.10/202014 1
• •
STORMWATER CALULATIONS—IMPERVIOUS SURFACE
NEW EXISTING
Structures(all roof area) 496 sq/ft Structures(all roof area) 2,990 sq/ft
Sidewalks 0 sq/ft Sidewalks 0 sq/ft
Patios 0 sq/ft Patios 0 sq/ft
Solid Decks 0 sq/ft Solid Decks 0 sq/ft
(without infiltration below) (without infiltration below)
Driveway, parking, roads, etc 970 sq/ft Driveway, parking, roads, etc 5,920 sq/ft
Other 0 sq/ft Other ,440 sq/ft
Total New
1 ,466 sq/ft Total Existing 1 0,350 sglft
TOTAL NEW+TOTAL EXISTING* 11 ,816 sq/ft "This amount will be used to check total lot coverage.
The following questions will help determine whether the proposed project is considered development or redevelopment.
DEVELOPMENT v. REDEVELOPMENT
Divide the total existing impervious surface above by the size of the parcel and convert to a percentage: 4.3
Does the site have 35%or more of existing impervious surface? Circle: Yes No ✓
FURTHER INSTRUCTIONS: If the answer is yes,the proposal is considered redevelopment and the attached Figure 2 should be used
to determine the applicable Minimum Requirements. If the answer is no, the proposal is considered new development and the
attached Figure 1 should be used. At this juncture, the applicant should refer to the applicable Flow Chart to determine the
Minimum Requirements for stormwater management. DCD staff will help verify the classification of the project and the application
requirements.
For proponents of "small" projects who must comply only with Minimum Requirement #2—Construction Stormwater Pollution
Prevention—an additional submittal is not required. The proponent is responsible for employing the 12 Elements to control erosion
and prevent sediment and other pollutants from leaving the site during the construction phase of the project. Pick up the
Construction Stormwater Pollution Prevention (SWPP) Best Management Practices (BMPs) Packet. Proponents of "medium"
projects—those that must meet only Minimum Requirements#1 through#5—and for"large" projects—those that must meet all 10
Minimum Requirements—are required to submit a Stormwater Site Plan. DCD has prepared a submittal template of a Stormwater
Site Plan, principally for rural residential projects. Complete the template in the Stormwater Site Plan Instructions and Submittal
Template or prepare a Stormwater Site Plan using the step-by-step guidance in the Storm water Management Manual.
APPLICANT SIGNATURE
By signing the Stormwater Calculation Worksheet,I as the applicant/owner attest that the information provided herein is true and correct to the
best of my knowledge. I also certify that this application is being made with the full knowledge and consent of all owners of the affected
property.
4v4dre i' l�r't�f
(L WNER OR AUTH RIZED REPRESENTATIVE SIGNATURE) (DATE)
FOR OFFICE USE ONLY
SMALL_ MEDIUM_ LARGE_ REDEVELOPMENT_ Stormwater Site Nan: Yes No
storrnwster calc worksheet—REV.10/20/2014 2
• •
FIGURE 1 : NEW DEVELOPMENT
Start Here
Does the site have Yes See Redevelopment
35%or more of Minimum
existing impervious Requirements and
coverage? Flow Chart
(Figure 2)
No Does the project convert'/.
acres or more of native
• vegetation to lawn or
Does the project add No landscaped areas, or
5,000 square feet or convert 2.5 acres or more
more of new of native vegetation to
impervious surfaces? pasture?
Yes Yes No
Does the project have
"LARGE"PROJECT 2,000 square feet or
more of new, replaced,
All Minimum Requirements or new plus replaced
apply to the new impervious impervious surfaces?
surfaces and converted
pervious surfaces. Yes
•
"MEDIUM"PROJECT Does the project have
Minimum Requirements #1 land-disturbing
•
through#5 apply to the new activities of 7,000
and replaced impervious Yes square feet or more?
surfaces and the land
disturbed.
•
"SMALL" PROJECT
See Minimum
Requirement#2,
Construction Stormwater
Pollution Prevention
Based on Fig.2.2 from 2001 Ecology Stormwater Management Manual for Western Washington
• •
cO� JEFFERSON COUNTY
4 < 04 DEPARTMENT OF COMMUNITY DEVELOPMENT
621 Shendan Street•Port Townsend•Washington 98368
.0 360/379.4450•360/379-4451 Fax
G~— http://www.co.jefferson.wa.us/commdevelopment/
STORMWATER SITE PLAN SUBMITTAL TEMPLATE
MLA# PROJECT/APPLICANT NAME
Project Overview
1. Describe the proposed developed conditions of the site. Indicate position and
relative size of proposed improvements on the site map.
The project site is located at 1452 Gardiner Beach Road; parcel number 002-284-020.
The lot is 5.5 acres in size with 10,350 sq. ft. (approximately 4.3%)of existing
impervious surfaces. There is an existing single family residence (SFR), gravel
driveway, and concrete slab. The proposed garage will be built in the location of the
existing slab (area= 1,440 sq. ft.). The garage is 1,568 sq. ft. with 1,936 sq. ft. of roof
area. There is an existing cleared area that is approximately 1.29 acres in size(56,192
sq.ft.). Approximately 1,466 sq. ft. of new impervious surfacing will be added, 970 sq. ft.
of driveway and an additional 496 impervious area(1,936 sq. ft. roof— 1,440 existing
slab),resulting in a 0.6% increase in impervious area(total 4.9%).
Existing Conditions Summary
2. Describe the existing topography. Indicate contours on the site map.
The site generally slopes north with an average slope of 10%.
3. Describe the existing vegetation. Indicate native vegetation areas on the site map.
Surrounding the proposed construction site and SFR are second growth trees and dense
vegetation. The previously cleared area has established grasses and shrubs.
4. Describe the existing soils. Indicate soil type on the site map.
Soils on site are classified by Jefferson County as Tukey gravelly loam (TuC). A typical
profile is described below:
• 0—2 inches: gravelly loam
• 2—8 inches: gravelly loam
• •
• 8—36 inches: very gravelly loam
• 36—60 inches: very gravelly loam
5. Describe the existing site hydrology (i.e., drainage; behavior of water on the
site—above, below, and on the ground). Indicate existing stormwater drainage to
and from the site on the site map. Depict separate drainage basins on the site map,
if applicable, and indicate acreage of each.
Stormwater onsite generally drains from south to north. There is a 400 foot(3.4 acres)
flow path to the north consisting of second growth trees and dense vegetation; little to no
stormwater leaves the site.
6. Describe any excess levels of noise generated by the proposed use or activity:
Excess noise will strictly be from construction. After completion of construction and
stabilization of disturbed soils,there will be no excess levels of noise.
7. Describe significant geographic features and critical areas (i.e., environmentally
sensitive areas such as wetlands, streams, steep slopes, etc.) on the site. Indicate
location on the site map.
None
8. Describe the general vicinity of the site, including adjacent land uses and
structures, utilities, roads,and sensitive/critical areas (streams,wetlands, lakes,
steep slopes,etc.).
There are no known critical or sensitive areas within or surrounding the property.
Adjacent properties are developed for rural (SFRs) use.
• •
Permanent Stormwater Control Plan
This portion of the Stormwater Site Plan consists of the selection and installation of
the appropriate stormwater control BMPs and facilities to remain in place after
construction of the project is completed.
"Medium" size projects are required to have the totals calculated of all impervious
surfaces,pollution-generating impervious surfaces, and pollution-generating
pervious surfaces to verify that the thresholds for treatment facilities and flow
control facilities are not exceeded.
9. Describe the developed site hydrology, as proposed. Indicate whether
stormwater will be fully dispersed (i.e.,per BMP T5.30 in the Manual) or, if not,
what types of stormwater flow control will be utilized for the site or specific
threshold discharge areas within the site. Locate these facilities on the site plan and
differentiate proposed facilities from existing facilities.
Developed site hydrology will mimic pre-construction conditions. Drainage will flow
south to north. Runoff from the garage roof will be collected in downspouts and
discharged onto splash blocks in compliance with BMP T5.10B, and Section 3.1.2 of
Volume III of the Stormwater Management Manual for Western Washington(DOE,
August 2012). Runoff from the gravel access will sheet flow west toward a 2' transition
zone that will disperse the sotrmwater west/northwest in compliance with BMP T5.12.
10. If the project requires the use of stormwater treatment facilities, describe the
types of stormwater treatment facilities proposed for use on the site. Locate these
facilities on the site plan and differentiate proposed facilities from existing facilities.
[This is normally for"large" projects or projects that involve the potential for
dispersion of contaminants.]
N/A, less than 5,000 sq. ft. pollution generating hard surfaces.
11. Describe the performance goals and standards applicable to the project.
N/A
12. Describe the flow control system.
N/A
13. Describe the water quality system.
N/A
14. Describe the conveyance system analysis and design.
• •
N/A, full dispersion will be utilized
15. Describe the source of fill material, physical characteristics of fill material, and
deposition of excess material.
N/A
16. Proposed methods of placement and compaction consistent with the applicable
standards on Appendix Chapter 33 of the Uniform Building Code.
N/A
17. Describe the proposed surfacing material.
Surfacing for access to the proposed garage will be clean gravel.
18. Describe methods for restoration of the site.
In compliance with BMP T5.13 a minimum of 8 inches of top soil will be use to amend
disturbed soils. The top soil will be mulched and seeded for final stabilization.
19. An Operation and Maintenance Manual is required for each flow control and
treatment facility. [This is normally required for "large" projects only and only
those for which facilities are required to control flow or treat runoff.] If included,
list the Manuals here.
N/A
20. List here and include any special reports or studies conducted to prepare the
Stormwater Site Plan.
None
21. List other necessary permits and approvals as required by other regulatory
agencies. If those permits or approvals include conditions that affect the drainage
plan or contain more restrictive drainage-related requirements, describe those
conditions or restrictions here.
None
• •
CONSTRUCTION STORMWATER POLLUTION PREVENTION
PLAN (SWPPP)
The Construction SWPPP addresses sediment and erosion control during construction.
The BMPs indicated by the applicant in the template that follows must be installed on the
ground during all construction phases of the project. The proponent is responsible for
preventing sediment and erosion impacts to environmentally sensitive areas and off-site
areas. Consult the Construction Stormwater Pollution Prevention(SWPP) Best
Management Practices (BMPs) Packet for guidance, particularly with rural residential
development.
SECTION I - CONSTRUCTION SWPPP NARRATIVE
1. Construction Stormwater Pollution Plan Elements. Describe how each of the
Construction SWPPP elements has been or will be addressed. Identify the type and
location of BMPs used to satisfy the required element. If an element is not applicable
to the proposal,justify in writing. Descriptions of the 12 Elements are found at section
2.5.2 of the Manual (beginning on page 2-15).
12 Required Elements—Construction SWPPP
1. Mark Clearing Limits.
No clearing activity will be needed for the proposal. Construction limits will be kept
close to the construction site in an effort to minimize site disturbance. If needed a 20'
offset will be staked and flagged to delineate the project area and approximate limits of
soils stabilization.
2. Establish Construction Access.
An existing gravel entry will be utilized as an established construction access and staging
area. The existing gravel driveway will be resurfaced as needed to prevent trackout..
3. Control Flow Rates.
Flow control is not needed for this proposal. All runoff will be fully dispersed.
4. Install Sediment Controls.
The dense woods and vegetation to the north will act as a natural vegetative strip in lieu
of a silt fence.
5. Stabilize Soils.
Disturbed soils will be amended in compliance with BMP T5.30 and mulched and seeded
for final stabilization.
• •
6. Protect Slopes.
N/A
7. Protect Drain Inlets.
N/A
8. Stabilize Channels and Outlets.
N/A
9. Control Pollutants.
N/A
10. Control De-Watering (the act of pumping groundwater or stormwater away
from an active construction site).
N/A
11. Maintain Best Management Practices (BMPs).
All BMP's will be checked bi weekly and after major storm events. Any damages or
deficiencies will be addressed promptly.
12. Manage the Project.
All BMP's will be inspected and maintained, temporary BMP's will be removed upon
confirmation of soil stabilization.
Adjacent Areas.
a. Description of the adjacent areas that may be affected by site disturbance
(e.g., streams, lakes, wetlands, residential areas, roads).
None known
• •
b. Description of the downstream drainage path leading from the site to the
receiving body of water (minimum distance of 400yards).
Water sheet flows north into dense woods.
Environmentally Sensitive Areas.
a. Description of environmentally sensitive areas that are on or adjacent to the site.
None known
b. Description of special requirements for working in or near environmentally
sensitive areas.
None
Erosion Problem Areas. Description of potential erosion problems on site in the
context of the characteristics of the on-site soils (e.g., erodibility, settleability,
permeability, depth, texture, soil structure).
None
Construction Phasing.
a. Construction sequence: Resurface gavel driveway as needed to prevent track out,
demolish and remove existing concrete foundation (if applicable), construct proposed
garage, amend disturbed soils, seed and mulch amended soil.
b. Construction phasing (if proposed)
Construction Schedule. Wet season is October 1 through April 30 (page 2-21 of
the Manual).
I. Provide a proposed construction schedule.
January 2015 —July 2015
II. Wet Season Construction Activities.
a. Proposed wet season construction activities:
None
b. Proposed wet season construction activities for environmentally sensitive areas.
N/A
• •
Financial/Ownership Responsibilities.
a. Identify the property owner responsible for the initiation of bonds and/or other
financial securities.
The property owner will be responsible for the initiation of bonds and/or other financial
securities.
b. Describe bonds and/or other evidence of financial responsibility for liability
associated with erosion and sedimentation impacts.
The contractor retained by the property owner will be held responsible for bonds and/or
evidence of financial responsibility for liability associated with erosions and
sedimentation impacts.
8. Engineering Calculations. Provide Design Calculations on a separate sheet for
the following,if applicable.
a. Sediment Ponds/Traps.
b. Diversions.
c. Waterways.
d. Runoff/Stormwater Detention Calculations
• •
Map Unit Description:Tukey gravelly loam,0 to 15 percent slopes---Jefferson County Area,
Washington
Jefferson County Area, Washington
TuC—Tukey gravelly loam, 0 to 15 percent slopes
Map Unit Setting
National map unit symbol: 2gtm
Mean annual precipitation: 21 inches
Mean annual air temperature: 50 degrees F
Frost-free period: 225 to 250 days
Farmland classification: Farmland of statewide importance
Map Unit Composition
Tukey and similar soils: 100 percent
Estimates are based on observations, descriptions,and transects of the
mapunit.
Description of Tukey
Setting
Landform: Terraces
Parent material: Basal till
Typical profile
H1 - 0 to 2 inches: gravelly loam
H2- 2 to 8 inches: gravelly loam
H3 - 8 to 36 inches: very gravelly loam
H4 -36 to 60 inches: very gravelly loam
Properties and qualities
Slope: 0 to 15 percent
Depth to restrictive feature: 20 to 40 inches to densic material
Natural drainage class: Moderately well drained
Capacity of the most limiting layer to transmit water(Ksat): Very low
to moderately low (0.00 to 0.06 in/hr)
Depth to water table: About 18 to 36 inches
Frequency of flooding: None
Frequency of ponding: None
Available water storage in profile: Low(about 3.9 inches)
Interpretive groups
Land capability classification (irrigated): None specified
Land capability classification (nonirrigated): 3e
Hydrologic Soil Group: C
Other vegetative classification: Droughty Soils(G002XN402WA)
Data Source Information
Soil Survey Area: Jefferson County Area, Washington
Survey Area Data: Version 13, Sep 30, 2014
USDA Natural Resources Web Soil Survey 1/16/2015
rill. Conservation Service National Cooperative Soil Survey Page 1 of 1